The invention relates to a spring assisted shock absorbing device of the type used in the suspension system of an automobile wherein the vertical relative movement of a telescoping shock absorbing unit is utilized in combination with a spring. Typically, coil springs have been used adjacent the shock absorbing unit or mounted about the shock absorbing unit in a concentric fashion to support the static load of the vehicle and also act as an overload spring.
The purpose of the vehicle suspension system is to support the vehicle's body and frame on the wheels and provide absorption of road shock caused by the passage of the wheels over irregularities. Heretofore, leaf springs, coil springs, torsion bar springs, and hydraulic springs have been utilized in the suspension systems of vehicles. The weight of the automobile is applied on initial compression to the springs and when the wheels encounter irregularities in the highway or other surface, the springs further compress to absorb the additional shock. The spring may also compress considerably due to heavy loading of the vehicle, or due to banking or leaning of the vehicle while undergoing curves or turns at high speeds.
Shock absorbing units are utilized in conjunction or as a replacement for springs to restrain excessive spring movement and prevent prolonged isolations which would provide a generally rougher ride.
The present invention is directed more particularly to shock absorbing units which are combined with a spring either externally or concentrically placed about the shock absorbing unit. Coil type springs have been commonly used to assist the shock absorbing unit by concentrically mounting the coil springs around the shock absorbing unit as shown in U.S. Pat. Nos. 3,951,391; 3,877,687; 3,251,591; and 3,181,852. These devices all employ coil springs typically fabricated from metal.
One of the problems of the combined spring and shock absorber is that the vehicle rides high and has a definite tendency to bounce when passing over highways or other surface irregularities. The coil spring has typically been manufactured from a metal. Due to the weight and mass of the metal coil spring, it requires considerable energy to stop its oscillations once it is deflected. Another problem with the concentrically mounted coil spring is that it may bind upon the shock absorber under heavy loads or deflections. Also, after repeated usage, the metal coil spring will lose its memory and become weakened in its capacity to absorb shock proportions.
Fiber reinforced material, such as fiberglass, has been utilized in automobile leaf springs and general spring devices such as shown in U.S. Pat. No. 2,913,240. However, the reinforcing characteristics of fibers present in these devices and arrangements of these devices have generally not made them applicable to use with coil spring arrangements. Telescoping parts have been utilized with other spring elements such as the exercise device shown in U.S. Pat. No. 3,958,803 which generally forms no part of the art related to vehicle suspension units.
Accordingly, an object of the present invention is to provide a light weight spring element for use in connection with a shock absorbing unit in the suspension system of a vehicle.
Another object of the invention is to provide a combined spring and shock absorbing unit having improved shock absorbing characteristics.
Another object of the invention is to provide a combination spring/shock absorbing unit in which a spring assists the shock absorbing unit and absorbs shocks from highway and other surface irregularities in a manner that undampened oscillations are greatly minimized.
Another object of the present invention is to provide a spring device for a vehicle suspension unit and the like having a spring which retains its memory and length during repeated loading so that the system uniformly acts to absorb road shocks.
Still another object of the invention is to provide a fiber reinforced spring which will handle compression loads in a vehicle suspension system and the like.